This is a randomized, double-blind, placebo-controlled Phase 2 study of MM-141 plus nab-paclitaxel and gemcitabine or placebo plus nab-paclitaxel and gemcitabine in front-line metastatic pancreatic cancer. All patients will be initially screened for free IGF-1 status. Eligible patients with high free IGF-1 will be randomized to receive MM-141 plus nab-paclitaxel and gemcitabine or placebo plus nab-paclitaxel and gemcitabine and patients. Patients with low free IGF-1 or patients who have high free IGF-1 but are not otherwise eligible will be followed in an observational group.